NCERT Solutions for Chapter: Classification of Elements and Periodicity in Properties, Exercise 1: EXERCISES

Why do elements in the same group have similar physical and chemical properties?

Assign the position of the element having outer electronic configuration $\left(\mathrm{n}-2\right) {\mathrm{f}}^7 \left(\mathrm{n}-1\right){\mathrm{d}}^1{\mathrm{ns}}^2$ for $\mathrm{n}=6$, in the periodic table.

The first $\left({\mathrm{\Delta }}_{\mathrm{i}}{\mathrm{H}}_1\right)$ and the second $\left({\mathrm{\Delta }}_{\mathrm{i}}{\mathrm{H}}_2\right)$ ionization enthalpies $\left(\mathrm{in} \mathrm{kJ} {\mathrm{mol}}^{-1}\right)$ and the $\left({\mathrm{\Delta }}_{\mathrm{eg}}\mathrm{H}\right)$ electron gain enthalpy $\left(\mathrm{in} \mathrm{kJ} {\mathrm{mol}}^{-1}\right)$ of a few elements are given below:

Which of the above elements is likely to be the least reactive element.

The first $\left({\mathrm{\Delta }}_{\mathrm{i}}{\mathrm{H}}_1\right)$ and the second $\left({\mathrm{\Delta }}_{\mathrm{i}}{\mathrm{H}}_2\right)$ ionization enthalpies $\left(\mathrm{in} \mathrm{kJ} {\mathrm{mol}}^{-1}\right)$ and the $\left({\mathrm{\Delta }}_{\mathrm{eg}}\mathrm{H}\right)$ electron gain enthalpy $\left(\mathrm{in} \mathrm{kJ} {\mathrm{mol}}^{-1}\right)$ of a few elements are given below:

Which of the above elements is likely to be the most reactive element?

The first $\left({\mathrm{\Delta }}_{\mathrm{i}}{\mathrm{H}}_1\right)$ and the second $\left({\mathrm{\Delta }}_{\mathrm{i}}{\mathrm{H}}_2\right)$ ionization enthalpies $\left(\mathrm{in} \mathrm{kJ} {\mathrm{mol}}^{-1}\right)$ and the $\left({\mathrm{\Delta }}_{\mathrm{eg}}\mathrm{H}\right)$ electron gain enthalpy $\left(\mathrm{in} \mathrm{kJ} {\mathrm{mol}}^{-1}\right)$ of a few elements are given below:

Which of the above elements is likely to be the most reactive non-metal.

The first $\left({\mathrm{\Delta }}_{\mathrm{i}}{\mathrm{H}}_1\right)$ and the second $\left({\mathrm{\Delta }}_{\mathrm{i}}{\mathrm{H}}_2\right)$ ionization enthalpies $\left(\mathrm{in} \mathrm{kJ} {\mathrm{mol}}^{-1}\right)$ and the $\left({\mathrm{\Delta }}_{\mathrm{eg}}\mathrm{H}\right)$ electron gain enthalpy $\left(\mathrm{in} \mathrm{kJ} {\mathrm{mol}}^{-1}\right)$ of a few elements are given below:

Which of the above elements is likely to be the least reactive non-metal.

The first $\left({\mathrm{\Delta }}_{\mathrm{i}}{\mathrm{H}}_1\right)$ and the second $\left({\mathrm{\Delta }}_{\mathrm{i}}{\mathrm{H}}_2\right)$ ionization enthalpies $\left(\mathrm{in} \mathrm{kJ} {\mathrm{mol}}^{-1}\right)$ and the $\left({\mathrm{\Delta }}_{\mathrm{eg}}\mathrm{H}\right)$ electron gain enthalpy $\left(\mathrm{in} \mathrm{kJ} {\mathrm{mol}}^{-1}\right)$ of a few elements are given below:

Which of the above elements is likely to be the metal which can form a stable binary halide of the formula ${\mathrm{MX}}_2$, $\left(\mathrm{X}=\mathrm{halogen}\right)$.

The first $\left({\mathrm{\Delta }}_{\mathrm{i}}{\mathrm{H}}_1\right)$ and the second $\left({\mathrm{\Delta }}_{\mathrm{i}}{\mathrm{H}}_2\right)$ ionization enthalpies (in $\mathrm{kJ} {\mathrm{mol}}^{–1}$) and the $\left({\mathrm{\Delta }}_{\mathrm{eg}}\mathrm{H}\right)$ electron gain enthalpy (in $\mathrm{kJ} {\mathrm{mol}}^{–1}$) of a few elements are given below:

Which of the above elements is likely to be the metal which can form a predominantly stable covalent halide of the formula $\mathrm{MX}$ ($\mathrm{X}$=halogen)?